Plasma sources for use in forming fine patterns on the surfaces of substrates have been developed into various shapes in view of the necessity of finely forming the line width of a circuit pattern in the field of semiconductors and in view of the necessity of increasing the size of a glass substrate in the field of LCDs made of glass substrates.
Typical examples of plasma sources for producing plasma in semiconductor manufacturing devices include a capacitively coupled plasma (CCP) source having a parallel plate geometry and an inductively coupled plasma (ICP) source using an antenna coil. The CCP source has been developed by Tokyo Electron Ltd., Japan and Lam Research Corp., U.S.A., and the ICP source has been developed by Applied Materials Technologies, Inc. and Lam Research Corp., U.S.A.
While the CCP source is advantageous in generating uniform plasma, an electromagnetic field has a direct influence on a substrate as a workpiece. Therefore, the electromagnetic field is apt to adversely affect the formation of a fine pattern on the workpiece. Furthermore, since the CCP source has plasma generation density smaller than that of the ICP source, the CCP source is disadvantageous in appropriately forming a pattern as a line width grows narrower. Moreover, as a high level of power is applied to the CCP source, severe damages may be caused to the workpiece and the semiconductor manufacturing device, which leads to increased manufacturing costs and difficulties.
On the other hand, the ICP source using an antenna coil to which high frequency power (or radio frequency power) is applied provides advantages in that it has an ability to generate plasma under a low pressure and enjoys an increased plasma generation density. However, the ICP source causes many problems to a substrate as a workpiece due to the non-uniform generation of plasma resulting inherently from the structure of the antenna. In the field of LCDs that makes use of glass substrates, the ICP source poses a problem in that plasma cannot be uniformly generated as the size of a glass substrate increases. Nevertheless, so long as uniformity is secured in the generation of plasma, the ICP source can serve as an excellent plasma source that can cope with the ultra-fineness of a circuit line width and the enlargement of a glass substrate. Thus, research has been keenly demanded for improving the structure of an antenna.